1. Field of the Invention
The invention is concerned with stabilized fuels and lubricants. More particularly, it relates to fuel and lubricant compositions to which have been added an aroyl derivative of an alkenylsuccinic anhydride.
2. Discussion of the Prior Art
A great deal of efforts is being directed to providing a lubricant which will permit present-day automotive engines to be operated at a high level of efficiency over long periods of time. A difficulty arises because lubricating oils tend to deteriorate under the conditions of use, with attendant formation of sludge, lacquer and resinous materials which adhere to the engines parts, thereby lowering the operating efficiency of the engine. To counteract the formation of these deposits, certain chemical additives have been found which, when added to lubricating oils, have the ability to keep the deposit-forming materials suspended in the oil, so that the engine is kept clean and in efficient operating condition for extended periods of time. These added agents are known in the art as detergents or dispersants.
Metallo-organic compounds are particularly useful as additives in this respect. However, the troublesome deposits which form on the skirt of the piston and on the walls of the combustion chamber, as well as on valves and spark plugs are also partially attributable to these metal containing additives employed in the lubricant. Whenever oil is burned in the engine, as occurs with the oil film present on the cylinder wall during the combustion stroke, many metal containing additives present in the oil may form an ash which is partially deposited on the various surfaces of the combustion chamber and on those of the spark plugs and valves.
Several known non-metallic detergents have previously been used in lubricating compounds. However, they have not proved to be entirely satisfactory. Additives which are particularly effective are based upon condensation products of a hydroxyaromatic compound, an aldehyde and an amine, the so-called Mannich reaction. These additives are multi-functional improvers especially adapted for mineral oils and as pour point depressants therein. These compounds have also been recognized as exhibiting detergent properties. A preference has existed for the use of hydroxyaromatics which are unsubstituted, particularly phenol and alpha and beta naphthols.
U.S. Pat. No. 3,808,131 discloses a metal coordinated complex, useful as a detergent in lube oils and fuels, made by reacting an amine-acid product with an alkenylsuccinic anhydride or acid and a metal salt. Further, U.S. Pat. No. 3,755,167 describes a lube or fuel additive prepared by reacting an amine-aldehyde product with an alkenylsuccinic acid or anhydride and a metal salt. This additive is also useful as a detergent.
Other patents include U.S. Pat. Nos. 3,215,728, 3,493,520, 3,522,179, 3,558,743 and 3,632,510.
U.S. Pat. No. 3,215,728 discloses the reaction between an alkylphenol and a diester of maleic acid. The phenol is attached directly to the maleate double bond, and there is no carbon chain on the molecule of 50 carbon atoms or more.
U.S. Pat. Nos. 3,493,520 and 3,558,743 relate to products made from succinic acid, amine, phenol and aldehyde. However, there is no disclosure in this patent of the necessity for having a C.sub.50 alkenyl on the succinic compound. In addition, it is evident that the products are in no way similar to those of the present invention since the phenol is not attached to the carbon system of the succinic compound, but to the imide formed during reaction (see Columns 5 and 6 of 3,493,520).
U.S. Pat. Nos. 3,522,179 and 3,632,510 disclose products made by reacting a hydrocarbon-substituted succinic anhydride with, for example, phenol, and salts thereof. It is obvious, however, that the products are different. In Column 5 of U.S. Pat. No. 3,522,179 and Column 6 of U.S. Pat. No. 3,632,510, it is shown that the hydroxyl compound reacts directly with the anhydride function to form the ester. This is precisely the reaction applicant wishes to avoid.